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Testing the HiRes Detector Simulation
against UHECR Data
Andreas Zech( Rutgers University)
for the HiRes - Fly´s Eye Collaboration
ICRC 2003 in Tsukuba
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HiRes CollaborationHiRes Collaboration
J.A. Bellido, R.W. Clay, B.R. Dawson, K.M. Simpson
University of Adelaide
J. Boyer, S. Benzvi, B. Connolly, C. Finley, B. Knapp, E.J. Mannel,
A. O’Neil, M. Seman, S. Westerhoff
Columbia University
J. Belz, M. Munro, M. Schindel
Montana State University
G. Martin, J.A.J. Matthews, M. Roberts
University of New Mexico
D. Bergman, L. Perera, S. Schnetzer, G.B. Thomson, A. Zech
Rutgers University
N. Manago, M. Sasaki
University of Tokyo
T. Abu-Zayyad, J. Albretson, G. Archbold, J. Balling, K. Belov, Z. Cao, M. Dalton,
A. Everett, J. Girard, R. Gray, W. Hanlon, P. Hüntemeyer, C.C.H. Jui, D. Kieda, K. Kim, E.C. Loh, K.
Martens, J.N. Matthews, A. McAllister, J. Meyer, S.A. Moore, P. Morrison, J.R. Mumford, K. Reil,R.
Riehle, P. Shen, J. Smith, P. Sokolsky, R.W. Springer, J. Steck, B.T. Stokes, S.B. Thomas,
T.D. Vanderveen, L. Wiencke
University of Utah
J. Amann, C. Hoffman, M. Holzscheiter, L. Marek, C. Painter, J. Sarracino, G. Sinnis, N. Thompson, D. Tupa
Los Alamos National Laboratory
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The HiRes FADC Detector (HiRes-2)
The newer one of the 2 HiRes air fluorescence detectors 2 rings with 21 mirrors each Located on Camel’s Back Ridge in Dugway (Utah) Started taking data in fall 1999
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The HiRes FADC Detector (HiRes-2)
256 photomultiplier tubes per mirror. Flash ADC electronics record at a frequency of 10 MHz.
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The Role of Monte Carlo Simulations in the HiRes
ExperimentWe need M.C. to calculate the acceptance of our detectors for the flux measurement:
M.C. is also a powerful tool for resolution studiesand for tests of our reconstruction programs. This requires a simulation program that describes the shower development and detector response as realistically as possible.
We want our code to simulate events under the exact data-taking conditions.
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HiRes Simulation Programs
HiRes FADC detector Monte Carlo choose energy & composition from measured
distributions; choose random geometry pick one shower from the library and scale it to energy choose trigger & atmosphere from databases generate detector response for this shower
CORSIKA & QGSJet Generation of Air Showers G.H. Fits to the Shower
Profiles
Shower Library one entry for each shower: energy primary particle zenith angle depth of first interaction 4 G. H. fit parameters
Database with Trigger Conditions Nightly ontime Trigger Gains Trigger Logic Dead Mirrors
Atmospheric Database Hourly Information about the Aerosol Profile of the Atmosphere from Laser Shots.
MC Output File in the same format as
real data
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M.C. Input Energy & Composition
The composition is chosen from our HiRes Stereo and HiRes/MIA measurement.
The Fly’s Eye Stereospectrum is used as aninput for the M.C.
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CORSIKA Shower Library (proton & iron)
Gaisser-Hillas fit to the shower profile:
Fit parameters scale with primary energy:
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Adding Noise to the M.C.
Ambient light level (low amplitude) can be measured from the width of the FADC pedestals.
Additional sky noise (high amplitude) is added to the M.C. to get agreement with data of a certain period.
FADC counts in all trigger channelsblack: datared: M.C.
total noise tubes distributionblack: datared: M.C.
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A few Data / Monte Carlo Comparisons
or: Testing how well we understand our experiment ...
HiRes-2 data shown from 12/99 until 09/01. ~ 556 Hours of good weather data. average atmosphere used for consistency with
HiRes-1. Statistics:
– rec. geometry: 6309 events– after all cuts: 2274 events
M.C. : ~ 4 x data statistics
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Signal tubes / χ of linear time fit
2
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Light per Track Length / Čerenkov Fraction
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Rp / Rp Resolution
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Energy / Energy Resolution
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HiRes-2 Exposure
Flux:
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HiRes-2 Energy Spectrum
HiRes-2 data from 12/’99 until 09/’01
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HiRes Mono Energy Spectra
HiRes-1 data from 06/’97 until 02/’03
HiRes-2 data from 12/’99 until 09/’01
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Conclusions Our data analysis relies on a realistic M.C.
simulation for the aperture calculation and for resolution studies.
We have generated air showers and detector response for the HiRes FADC detector under the exact data-taking conditions.
We have tested our simulation successfully against data taken by HiRes-2.
Our M.C. simulation provides a realistic and detailed model of our experiment.